How Long Is A Day On Earth?
32.7 هزار بار بازدید -
9 سال پیش
-
I'm going to ask you
I'm going to ask you how long a day is on Earth, and you're going to get the haunting suspicion that this is a trap. Your instincts are right, it's a trap! The answer may surprise you.
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Team: Fraser Cain - @fcain
Jason Harmer - @jasoncharmer
Susie Murph - @susiemmurph
Brian Koberlein - @briankoberlein
Chad Weber - [email protected]
Kevin Gill - @kevinmgill
Created by: Fraser Cain and Jason Harmer
Edited by: Chad Weber
Music: Left Spine Down - “X-Ray”
Left Spine Down - Side Effect (new tr...
How long is a day on Earth? Or more specifically, how long does it take for the Earth to turn once on its axis? For all the stars to move through the sky and return to their original position? Go ahead, and yell your answer answer at the screen… 24 hours?
Wrong!
It only takes 23 hours, 56 minutes and 4.0916 seconds for the Earth to turn once its axis. Unless that’s what you said. In which case, congratulations!
I’m sure you’re now stumbling around in an incoherent state, trying to understand how you could have possibly messed this up. Were you reprogrammed by the hidden chronology conspiracy? Have time travellers been setting back all your clocks every day by 4 minutes? How was your whole life a lie?
Here’s the deal. When you consider a day, you’re probably thinking of your trusty clock, or maybe that smartphone lock screen that clearly measures 24 hours.
What you have come to understand as a “day” is classified by astronomers as a solar day. It’s the amount of time it takes for the Sun to move through the sky and return to roughly the same spot.
This is different from the amount of time it takes for the Earth to turn once on its axis - the 23 hours, 56 minutes. Also known as a sidereal day.
Why are these two numbers different? Imagine the Earth orbiting the Sun, taking a full 365 days, 5 hours, 48 minutes and 46 seconds to complete the entire journey. At the same time, the Earth is spinning on its axis.
Each day that goes by, the Earth needs to turn a little further for the Sun to return to the same place in the sky.… And that extra time is about 4 minutes.
If we only measured sidereal days, the position of the Sun would slip back, day after day. For half of the year, the Sun would be up between 12am and 12pm, and for the other half, it would be between 12pm and 12am. There would be no connection between what time it is, and whether or not the Sun is in the sky.
Can you imagine teaching your children how to read a clock, and then getting them to multiply that by the calendar to figure out when My Little Pony: Friendship is Magic starts? Madness.
Better to keep them in the dark, teach them that a day is 24 hours, and deny all knowledge when they get a little older, and start to ask you challenging questions. But pedants among you already knew that, didn’t you?
You already knew that a sidereal day is a little shorter than a solar day, and that everyone else has been living a lie. You’re the only one who can read the signs and know the terrifying truth. Aren’t you? Well, I’m here to tell you that you’re wrong too. There’s a deeper conspiracy that you’re not a part of. Dear Pedant, your life is also a lie.
The axis of the Earth’s pole, the imaginary line that you could draw between the south pole and the north pole is currently pointed roughly at Polaris, aka The North Star. But we’re wobbling like a top, and where the axis is pointing is slowly precessing westward over the course of 26,000 years.
--------
When did you discover your whole life was a lie? Tell us in the comments below.
Don’t forget to stick around for the blooper.
Thanks for watching! Click subscribe or like it on Facebook, never miss an episode.
If you’re into other big facts about the Universe here’s a link to our Earth playlist.
Thanks to Pamela J Stewart, Daniel Meeks, and the members of the Guide to Space community who keep these shows rolling. Love space science? Want to see episodes before anyone else? Get extras, contests, and shenanigans with Jay, myself and the rest of the team. Get in on the action. Click here.
Support us at: Patreon: universetoday
More stories at: http://www.universetoday.com/
Follow us on Twitter: @universetoday
Follow us on Tumblr: Tumblr: universetoday
Like us on Facebook: Facebook: universetoday
Google+ - https://plus.google.com/+universetoday/
Instagram - Instagram: universetoday
Team: Fraser Cain - @fcain
Jason Harmer - @jasoncharmer
Susie Murph - @susiemmurph
Brian Koberlein - @briankoberlein
Chad Weber - [email protected]
Kevin Gill - @kevinmgill
Created by: Fraser Cain and Jason Harmer
Edited by: Chad Weber
Music: Left Spine Down - “X-Ray”
Left Spine Down - Side Effect (new tr...
How long is a day on Earth? Or more specifically, how long does it take for the Earth to turn once on its axis? For all the stars to move through the sky and return to their original position? Go ahead, and yell your answer answer at the screen… 24 hours?
Wrong!
It only takes 23 hours, 56 minutes and 4.0916 seconds for the Earth to turn once its axis. Unless that’s what you said. In which case, congratulations!
I’m sure you’re now stumbling around in an incoherent state, trying to understand how you could have possibly messed this up. Were you reprogrammed by the hidden chronology conspiracy? Have time travellers been setting back all your clocks every day by 4 minutes? How was your whole life a lie?
Here’s the deal. When you consider a day, you’re probably thinking of your trusty clock, or maybe that smartphone lock screen that clearly measures 24 hours.
What you have come to understand as a “day” is classified by astronomers as a solar day. It’s the amount of time it takes for the Sun to move through the sky and return to roughly the same spot.
This is different from the amount of time it takes for the Earth to turn once on its axis - the 23 hours, 56 minutes. Also known as a sidereal day.
Why are these two numbers different? Imagine the Earth orbiting the Sun, taking a full 365 days, 5 hours, 48 minutes and 46 seconds to complete the entire journey. At the same time, the Earth is spinning on its axis.
Each day that goes by, the Earth needs to turn a little further for the Sun to return to the same place in the sky.… And that extra time is about 4 minutes.
If we only measured sidereal days, the position of the Sun would slip back, day after day. For half of the year, the Sun would be up between 12am and 12pm, and for the other half, it would be between 12pm and 12am. There would be no connection between what time it is, and whether or not the Sun is in the sky.
Can you imagine teaching your children how to read a clock, and then getting them to multiply that by the calendar to figure out when My Little Pony: Friendship is Magic starts? Madness.
Better to keep them in the dark, teach them that a day is 24 hours, and deny all knowledge when they get a little older, and start to ask you challenging questions. But pedants among you already knew that, didn’t you?
You already knew that a sidereal day is a little shorter than a solar day, and that everyone else has been living a lie. You’re the only one who can read the signs and know the terrifying truth. Aren’t you? Well, I’m here to tell you that you’re wrong too. There’s a deeper conspiracy that you’re not a part of. Dear Pedant, your life is also a lie.
The axis of the Earth’s pole, the imaginary line that you could draw between the south pole and the north pole is currently pointed roughly at Polaris, aka The North Star. But we’re wobbling like a top, and where the axis is pointing is slowly precessing westward over the course of 26,000 years.
--------
When did you discover your whole life was a lie? Tell us in the comments below.
Don’t forget to stick around for the blooper.
Thanks for watching! Click subscribe or like it on Facebook, never miss an episode.
If you’re into other big facts about the Universe here’s a link to our Earth playlist.
Thanks to Pamela J Stewart, Daniel Meeks, and the members of the Guide to Space community who keep these shows rolling. Love space science? Want to see episodes before anyone else? Get extras, contests, and shenanigans with Jay, myself and the rest of the team. Get in on the action. Click here.
9 سال پیش
در تاریخ 1394/08/14 منتشر شده
است.
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